Immunogenicity of various presentation forms of PorA outer membrane protein of Neisseria meningitidis in mice

In this study we compare different vaccine formulations containing meningoc occal PorA outer membrane protein; purified PorA, outer membrane vesicles ( OMV) and immune-stimulating complexes (iscom). Bactericidal antibodies coul d be generated by the OMV and iscom formulation but not with purified PorA using either AlPO4 or Quil-A as adjuvant. OMV and iscom formulations reveal ed similar immunogenicity when tested in a dose response manner, with respe ct to bactericidal as well as OMV-binding antibodies. The anti-OMV IgG subc lass response induced by PorA in OMV formulation was found in all subclasse s IgG1, IgG2a, IgC2b, IgG3, OMP-iscoms induced very high IgG1 anti-OMV anti bodies but almost no IgG3 response. Also, OMP iscoms appeared to be a poten t inducer of antibodies directed against linear peptides corresponding to s urface exposed loops of PorA. In addition, iscoms as well as purified PorA with Quil-A as adjuvant (but not with AlPO4) induced high levels of antibod ies against purified PorA. In summary, in addition to the OMV formulation, only iscoms containing PorA are able to generate an anamnestic and bacteric idal antibody response. (C) 1999 Published by Elsevier Science Ltd. All rig hts reserved.